Electrical signal wires of shaft mounted position encoder sensors reduce the robustness of the overall generator control system due to significant mechanical vibration that exists on the turbine driven train.
Conventional Back Electromotive Force (Bemf) observation based position sensorless control methods for Interior Permanent Magnet (IPM) machines may not work well at speeds close to standstill where the generator Bemf voltage level is very low.
The performance of the conventional high frequency carrier signal injection methods, which utilizes the inductance saliency of IPM machine, is derived from the stator voltage equation. Simplification is made to ignore the effect of stator resistance variation and the effect of the fundamental frequency component so that the high frequency impedance matrix can be derived. By principle, this prior art method is sensitive to stator resistance variation and it may not be applicable for high speed operation.
According to prior art methods, the estimated position error function is based on a high frequency impedance matrix which is derived from the stator voltage equation. In these methods assumptions are made that the stator resistance variation is negligible and the fundamental frequency is very low. These assumptions make prior art methods sensitive to stator resistance variation and they are not suitable for high speed operation.